1. Field of the Invention
The present invention relates to a cooling system for a Stirling engine and more particularly, to a cooling system for a Stirling engine in which operating fluid of the engine is cooled by utilizing a thermoelectric heat pump so that continuous circulation of cooling water is not required and heat taken out of operating fluid is made to be used for the pre-heating of air to be fed to a combustion chamber.
2. Field of the Prior Art
Generally, various types of Stirling engines utilized are well known in the art. Such Stirling engines suffer from a number of problems such as, for example, (a) when the gas is heated within hermetically sealed container, the pressure is raised, and (b) when the gas is cooled, the pressure is dropped. One of such Stirling engines will be described in detail with reference to the accompanying drawings as followings:
As shown in FIG. 3, a conventional Stirling engine comprises a power piston 2 and a displacer 3 within a cylinder 1, a power chamber 4 disposed in the middle portion of the cylinder 1 for compressing operating fluid, a hot space 5 disposed at the upper portion of the cylinder 1 for expanding the operation fluid, a combustion chamber 6 disposed at the top portion of the cylinder 1, an air pre-heater 7 disposed at a side of the combustion chamber 6 for heating and feeding the external air to the combustion chamber 6, and a regenerator 8 disposed around the upper portion of the cylinder 1, whereby the regenerator 8 and the power chamber 4 are connected with cooling pipes 9 and a cooling chamber 10 is disposed around the cooling pipes 9 for circulating the cooling water, and the regenerator 8 and the hot space 5 are connected with heating pipes 11. In the drawings, reference numeral 7a represents an inlet for the air pre-heater 7, and reference numerals 10a and 10b represent inlet and outlet of the cooling chamber 10, respectively.
Thus such conventional Stirling engine is provided that when the operating fluid passes from the power chamber 4 through the cooling pipes 9, regenerator 8, and finally the heating pipes 11, the heat of the combustion chamber 6 is received, whereby the pressure is increased. Therefore, this increased pressure is operated to the power piston 2, whereby sometimes, the power piston 2 according to such conventional Stirling engine is made to be dropped down. On the contrary, when the operating fluid passes from the hot space 5 through the heating pipes 11, the regenerator 8, and finally the cooling pipes 9, the operating fluid is cooled and pressure is dropped, whereby the power piston 2 is raised. Therefore, in the Stirling engine, when the operating fluid is heated, the power piston 2 is dropped and when the operating fluid is cooled, the power piston 2 is raised. Thus when such reciprocating movement of the power piston 2 is repeated, the useful power is obtained therefrom.
In such conventional Stirling engine as described above, the cooling system is made such a manner that the cooling chamber 10 is disposed around the cooling pipes 9 and the interior of the cooling chamber 10 is made to flow with cooling water from the inlet 10a to the outlet 10b so that the operating fluid within the cooling pipe 9 is cooled. Therefore, since such conventional cooling system always requires supply of cooling water, it is a number of difficulties in supplying the cooling water in the area of lack in water, thereby having many limitations in using. In addition, the heat to be cooled by the operating fluid is not utilized again for the operation of such conventional Stirling engine and has to be discharged to exterior. Therefore, the heat loss has been much.
For instance of reference, the heat loss according to the cooling water may be counted as an amount of about 30-40% of heat supplied to the engine.